Mature language users are highly specialized, expert, and efficient perceivers and producers of their native language. This expertise begins to develop in infancy, a time when the infant acquires language-specific perception of native language phonetic categories and learns to produce speech-like syllables in the form of canonical babble. The emergence of these skills is well described by past research but the precise mechanisms by which these foundational abilities develop have not been identified. This chapter provides an overview of what is currently known about the impact of language experience on the development of speech perception and production during infancy. Throughout we affirm that experiential influences on phonetic development cannot be understood without considering the interaction between the constraints that the child brings to the task and the nature of the environmental input. In the perception and production domains our current understanding of this interaction is incomplete and tends to focus on the child as a passive receiver of input. In our review, we signal a recent shift in research attention to the infant’s role in actively selecting and learning from the input. We begin this chapter by describing what is currently known about the determinants of speech perception and speech production development during infancy while highlighting important gaps to be fi lled within each domain. We close by emphasizing the need to integrate research across the perception and production domains.